Wireless power transmission apparatus and wireless power transmission method

ABSTRACT

A wireless power transmission method of a wireless power transmitter can include detecting a first wireless power receiver for charging through a first power transmission scheme; attempting to charge the first wireless power receiver when the first wireless power receiver is detected; proceeding to charge the first wireless power receiver to a first charging power; detecting a second wireless power receiver for charging through a second power transmission scheme when the first wireless power receiver is not detected or when charging the first wireless power receiver fails even after the wireless power transmitter attempted to charge the first wireless power receiver; attempting to charge the second wireless power receiver when the second wireless power receiver is detected; and proceeding to charge the second wireless power receiver to a second charging power.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.15/380,685, filed on Dec. 15, 2016, which is a Continuation of U.S.application Ser. No. 15/044,996 (now U.S. Pat. No. 9,559,553 issued onJan. 31, 2017), filed on Feb. 16, 2016, which claims the benefit under35 U.S.C. § 119(a) to Patent Application No. 10-2015-0023677, filed inKorea on Feb. 16, 2015, all of which are hereby expressly incorporatedby reference into the present application.

BACKGROUND OF THE INVENTION

The embodiment relates to a wireless power transmission apparatus and awireless power transmission method.

In general, various electronic devices are equipped with batteries andoperated using power charged in the batteries. In this case, the batteryis replaceable and rechargeable in the electronic device. To this end,the electronic device is equipped with a connecting terminal for aconnection with an external charging device for charging the battery. Inother words, the electronic device is electrically connected with thecharging device through the connecting terminal. However, because theconnecting terminal in the electronic device is exposed to the outside,the connecting terminal may be contaminated with foreign matters orshorted due to moisture. In this case, connection failures occur betweenthe connecting terminal and the charging device so that the battery inthe electronic device may not be charged.

In order to solve the above problem, there has been suggested a wirelesspower charging system. The wireless power charging system includes awireless power transmission apparatus and a wireless power receptionapparatus. In this case, the electronic device is implemented as thewireless power reception apparatus. In addition, the wireless powertransmission apparatus transmits the power through a wirelesstransmission unit and the wireless power reception apparatus receivesthe power through a wireless reception unit.

A scheme of implementing a wireless charging system is typicallyclassified into a magnetic induction scheme and a magnetic resonancescheme.

The magnetic induction scheme is a contactless energy transmissiontechnique which applies current to one of two adjacent coils andgenerates electromotive force in the other coil through a medium of amagnetic flux generated from one coil, and the magnetic induction schememay utilize a frequency of several hundreds of kHz.

The magnetic resonance scheme is a magnetic resonance technique whichuses an electric or magnetic field without using any electromagneticwaves or electric currents, and the magnetic resonance scheme may have atransmissible distance of several meters or more and use a bandwidth ofseveral tens of MHz.

If the wireless power transmission apparatus is constructed with thecombination of the above charging schemes, the magnetic fields generatedfrom the coils may interfere with each other so that the two chargingmodes may not normally operate. In addition, if the independent chargingscheme is adopted, the high cost and degradation of components may becaused because installation and setting of dedicated hardware andsoftware are required.

SUMMARY OF THE INVENTION

The embodiment provides a wireless power transmission apparatusrepresenting improved performance.

The embodiment provides a wireless power transmission apparatus operatedwith various wireless power transmission schemes.

The embodiment provides a wireless power transmission apparatusincluding a first power converting unit to generate high-frequency ACsignals; a second power converting unit to generate low-frequency ACsignals; a first coil receiving the high-frequency AC signals andtransmitting a wireless power through a first power transmission scheme;a second coil receiving the low-frequency AC signals and transmittingthe wireless power through a second power transmission scheme; and acontrol unit to control the first and second coils, wherein the controlunit is configured to transmit a detection signal for the first powertransmission scheme to a wireless power reception apparatus through thefirst coil, detect a reception of a first response signal correspondingto the first detection signal during a first predetermined time,determine a power transmission scheme of the wireless power receptionapparatus as the first power transmission scheme in response to adetection of the first response signal, and deactivate the first powerconverting unit in response to no detection of the first responsesignal.

The embodiment provides a wireless power transmission method includingactivating a first transmission control unit that detects a first powertransmission scheme; transmitting a detection signal for the first powertransmission scheme to a wireless power reception apparatus; detecting areception of a first response signal corresponding to the firstdetection signal during a first predetermined time; determining a powertransmission scheme of the wireless power reception apparatus as thefirst power transmission scheme in response to a detection of the firstresponse signal; and deactivating the first transmission control unit inresponse to no detection of the first response signal.

The wireless power transmission apparatus according to the embodiment isa combination type wireless power transmission apparatus equipped withinduction and resonance schemes, which can provide maximum power throughvarious schemes with a simple configuration and reduce the cost throughthe common use of components.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an equivalent circuit of a magnetic induction scheme.

FIG. 2 is an equivalent circuit of a magnetic resonance scheme.

FIG. 3 is a block diagram showing a wireless power transfersystem-charger, which is one of a sub-system constituting a wirelesspower transfer system.

FIG. 4 is a block diagram showing a wireless power transfersystem-device, which is one of a sub-system constituting the wirelesspower transfer system.

FIG. 5 is a block diagram showing a wireless power transmissionapparatus according to an embodiment.

FIG. 6 is a flowchart showing a wireless power transmission operationaccording to one embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, a wireless power transfer system according to an embodimentwill be described with reference to accompanying drawings. Althoughembodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. The thickness and size of an apparatus shown in thedrawings may be exaggerated for the purpose of convenience or clarity.The same reference numerals denote the same elements throughout thespecification.

The embodiment selectively uses various types of frequency bandwidths inthe range of a low frequency wave (50 kHz) to a high frequency wave (15MHz) for transmitting wireless power, and requires a support of acommunication system which is capable of exchanging data and controlsignals for system control.

The embodiment can be employed in various industrial fields, such as amobile terminal industry, a smart clock industry, a computer and laptopindustry, an electronic device industry, an electric vehicle industry, amedical device industry, a robot industry, etc.

The embodiment may include a system capable of transmitting power to oneor more devices by using one or multiple transmission coils constitutingthe device.

According to the embodiment, the problem of low battery for mobiledevices such as smartphones, laptops, etc. can be solved. For example,when the smartphone and the laptop are seated and used on a wirelesscharging pad on a table, the battery is automatically charged and usedfor a long period of time. In addition, when the wireless charging padis installed at public areas such as coffee shops, airports, taxis,offices, restaurants, etc., various mobile devices can be chargedregardless of charging terminals which may vary depending on themanufacturer of the mobile device. Further, when the wireless powertransfer technology is employed in electrical appliances such as vacuumcleaners, electric fans, etc., users may not need to look for the powercable, and tangled electrical cables can be eliminated at home sowirings in buildings can be reduced and space can be more efficientlyutilized. In addition, a long period of time is required when anelectric vehicle is charged by a typical household power source.However, when a high amount of power is transmitted through the wirelesspower transfer technology, charging time can be reduced, and whenwireless charging equipment is installed at a floor of a parking lot, aninconvenience of preparing a power cable in the vicinity of theelectrical vehicle can be relieved.

Terms and abbreviations used in the embodiment are as follows.

Wireless Power Transfer System: A system for transmitting wireless powerin a magnetic field region.

Wireless Power Transfer System-Charger: An apparatus for transmittingwireless power to a signaler or multiple power devices in a magneticfield region and for managing the entire system.

Wireless Power Transfer System-Device: An apparatus for receivingwireless power from a wireless power transfer system-charger in amagnetic field region.

Charging Area: An area in which the wireless power is transmitted in themagnetic field region, and which may vary according to a size of anapplication product, required power and an operating frequency.

Scattering parameter: A scattering parameter is a ratio of an inputvoltage to an output voltage in a frequency distribution, a ratio of aninput port to an output port (Transmission; S21) or a self-reflectionvalue of each input/output port, in other words, a value of an outputreflecting back by a self-input (Reflection; S11, S22).

Quality factor (Q): A value of Q in a resonant state designates aquality of frequency selection, in which a resonance characteristic isbetter when the value of Q is higher, and the value of Q is expressed asa ratio of stored energy to energy loss in a resonator.

The principle of wirelessly transferring power mainly includes amagnetic induction scheme and a magnetic resonance scheme.

The magnetic induction scheme is a contactless energy transmissiontechnique which applies current to a source inductor Ls adjacent to aload inductor L1 such that electromotive force is generated in the loadinductor L1 through a medium of a magnetic flux generated from thesource inductor Ls. In addition, the magnetic resonance scheme generatesa magnetic resonance from a natural frequency between two resonators bycoupling the two resonators to utilize a resonance scheme for forming anelectric field and a magnetic field in the same wavelength range whilefluctuating in a same frequency thereby wirelessly transferring energy.

FIG. 1 is an equivalent circuit of a magnetic induction scheme.

Referring to FIG. 1, in the equivalent circuit of the magnetic inductionscheme, the wireless power transfer system-charger may be implemented bya source voltage V_(s) according to an apparatus for supplying power, asource resistance Rs, a source capacitor C_(s) for impedance matchingand a source coil Ls for a magnetic coupling with the wireless powertransfer system-device. The wireless power transfer system-device may beimplemented by a load resistance R₁ which is an equivalent resistance ofthe wireless power transfer system-device, a load capacitor C₁ forimpedance matching, and a load coil L₁ for the magnetic coupling withthe wireless power transfer system-charger, in which the degree ofmagnetic coupling between the source coil L_(s) and the load coil Li₁may be denoted as a mutual inductance Ms₁ .

In FIG. 1, a ratio S21 of an input voltage to an output voltage from amagnetic induction equivalent circuit including only a coil without thesource capacitor C_(s) and the load capacitor C₁ for the impedancematching is calculated and when a maximum power transmission conditionis found from the calculation, the maximum power transmission conditionsatisfies the following equation 1.

Equation 1

L _(s) /R _(s) =L ₁/R₁

According to the equation 1, a maximum power transmission is possiblewhen a ratio of an inductance of the transmission coil L_(s) to thesource resistance R_(s) is the same as a ratio of an inductance of theload coil L₁ to the load resistance R₁ . Because a capacitor forcompensating for a reactance does not exist in a system in which only aninductance exist, a self-reflection value S11 of an input/output port ata position on which maximum power is transferred may not be 0, and amaximum transfer efficiency may be varied according to the mutualinductance Ms₁. Accordingly, the source capacitor C_(s) may be added tothe wireless power transfer system-charger and the load capacitor C₁ maybe added to the wireless power transfer system-device for compensationcapacitors for the impedance matching. The compensation capacitors C_(s), C₁, for example, may be serially connected or connected in parallelwith each of the reception coil L_(s) and the load coil L₁,respectively. In addition, passive elements such as an additionalcapacitor and an inductor may be added along with the compensationcapacitors to each of the wireless power transfer system-charger and thewireless power transfer system-device for the impedance matching.

FIG. 2 is an equivalent circuit of a magnetic resonance scheme.

Referring to FIG. 2, in the magnetic resonance scheme equivalentcircuit, the wireless power transfer system-charger may be implementedby a source coil forming a closed loop circuit by a serial connection ofthe source voltage V_(s) the source resistance R_(s) and the sourceinductor L_(s) , and a transmission side resonance coil forming a closedloop circuit by a serial connection of a transmission side resonanceinductor L₁ and a transmission side resonance capacitor C₁, the wirelesspower transfer system-device may be implemented by a load coil forming aclosed loop circuit by a serial connection of the load resistance R₁ andthe load inductance L₁ and a reception side resonance coil forming aclosed loop circuit of a reception side resonance inductor L2 and areception side resonance capacitor C₂, in which the source inductor (Ls)and the transmission side inductor L₁ are magnetically coupled in acoupling coefficient of K01, the load source inductor L_(s) and the loadside resonance inductor L₂ are magnetically coupled in a couplingcoefficient of K23, and the transmission side resonance inductor L₁ andthe reception side resonance inductor L₂ are magnetically coupled in acoupling coefficient of K12.

In the magnetic resonance scheme, most of the energy in the resonator ofthe wireless power transfer system-charger is transferred to theresonator of the wireless power transfer system-device when theresonance frequency of the two resonators are the same, so that thepower transfer efficiency can be improved and the efficiency of themagnetic resonance scheme becomes better when satisfying the followingequation 2.

Equation 2: k/Γ>>1 (k is a coupling coefficient, F is a damping ratio)

In the magnetic resonance scheme, an element for the impedance matchingmay be added to improve the efficiency, and the impedance matchingelement may be a passive element such as an inductor and a capacitor.

A system for transmitting wireless power, in which power is transferredby the magnetic induction scheme or the magnetic resonance scheme basedon the principle for transmitting wireless power, will be examinedbelow.

FIG. 3 is a block diagram showing a wireless power transfersystem-charger, which is one of a sub-system constituting a wirelesspower transfer system.

Referring to FIG. 3, the system for transmitting wireless power mayinclude the wireless power transfer system-charger 1000 and the wirelesspower transfer system-device 2000 which wirelessly receives power fromthe wireless power transfer system-charger 1000, in which the wirelesspower transfer system-charger 1000 may include a transmission side AC/DCconverting unit 1100, a transmission side DC/AC converting unit 1200, atransmission side impedance matching unit 1300, a transmission coil unit1400 and a transmission side communication and control unit 1500.

The transmission side AC/DC converting unit 1100 is a power converterwhich converts an AC signal received from the outside under the controlof the transmission side communication and control unit 1500 to a DCsignal, in which the transmission side AC/DC converting unit 1100 may bea sub-system including a rectifier 1110 and a transmission side AC/DCconverter 1120. The rectifier 1110 is a system for converting thesupplied AC signal to the DC signal, and for an embodiment forimplementing the rectifier 1110, a diode rectifier having a relativelyhigh efficiency when operating at high frequencies, a synchronousrectifier prepared as one-chip, or a hybrid rectifier by which cost andspace can be reduced and having a high freedom of a dead time may beused. In addition, the transmission side DC/DC converter 1120 controls alevel of the DC signal provided by the rectifier 1100 under the controlof the transmission side communication and control unit 1500, and for anembodiment for implementing the transmission side DC/DC converter 1120,a buck converter which lowers a level of the input signal, a boostconverter which increases the level of the input signal and a buck boostconverter or a Cuk converter which lowers or increases the level of theinput signal may be used. In addition, the transmission side DC/DCconverter 1120 may include a switching device which controls a powerconversion, an inductor and a capacitor which smooth the output voltage,and a transformer which modifies a voltage gain or performs anelectrical separation (insulation) function, and remove a ripplecomponent or a pulsation component (AC component included in DCcomponent) included in the DC signal. Further, an error between acommand value of the output signal of the transmission side DC/DCconverter 1120 and an actual output value may be controlled through afeedback scheme, which can be performed by the transmission sidecommunication and control unit 1500.

The transmission side DC/AC converter 1200 is a system capable ofconverting the DC signal outputted from the transmission side AC/DCconverting unit 1100 to the AC signal under the control of thetransmission side communication and control unit 1500 and controlling afrequency of the converted AC signal, and for an embodiment forimplementing the transmission side DC/AC converter 1200, a half bridgeinverter or a full bridge inverter may be used. In addition, thetransmission side DC/AC converter 1200 may include an oscillator togenerate the frequency of the output signal and a power amplifying unitto amplify the output signal.

The transmission side impedance matching unit 1300 minimizes areflection wave at a position at which impedances are different therebyimproving a flow of the signal. The two coils of the wireless powertransfer system-charger 1000 and the wireless power transfersystem-device 2000 are spatially separated from each other so a largeamount of the magnetic field is leaked, so that an efficiency of powertransfer may be improved by compensating for the impedance differencebetween the two connecting parts of the wireless power transfersystem-charger 1000 and the wireless power transfer system-device 2000.The transmission side impedance matching unit 1300 may include aninductor, a capacitor and a resistor, and may modify an impedance valuefor the impedance matching by varying an inductance of the inductor, acapacitance of the capacitor and a resistance value of the resistorunder the control of the transmission side communication and controlunit 1500. In addition, when the wireless power transfer systemtransfers power by the magnetic induction scheme, the transmission sideimpedance matching unit 1300 may have a serial resonance structure or aparallel resonance structure, and energy loss can be minimized byincreasing an induction coupling coefficient between the wireless powertransfer system-charger 1000 and the wireless power transfersystem-device 2000. Further, when the wireless power transfer systemtransfers power by the magnetic resonance scheme, the transmission sideimpedance matching unit 1300 allows the impedance to be matched inreal-time according to a change in the distance between the wirelesspower transfer system-charger 1000 and the wireless power transfersystem-device 2000 or mutual influence from metallic foreign substancesand various devices, and a multiple matching scheme using a capacitor, amatching scheme using multiple antennas, a scheme using multiple loopsmay be used for the compensation scheme.

The transmission side coil 1400 may be implemented by a plurality ofcoils or a single coil, and, when the transmission side coil 1400includes a plurality of coils, the coils may be spaced apart from eachother or overlapping, and when the coils are overlapping, an overlappedarea may be determined by taking a deviation of the magnetic fluxdensity into consideration. In addition, the transmission side coil 1400may be produced by taking an internal resistance and a radiationresistance into consideration, and in this case, when the resistancecomponent is small, the quality factor and the transmission efficiencycan be improved.

The communication and control unit 1500 may be a sub-system including atransmission side controller 1510 and a transmission side communicationunit 1520. The transmission side controller 1510 may control the outputvoltage of the transmission side AC/DC converter 1100 by considering anamount of required power, a currently charged amount and a wirelesspower scheme of the wireless power transfer system-device 2000. Inaddition, the power to be transmitted may be controlled by generating afrequency and a switching waveform to drive the transmission side DC/ACconverter 1200 by taking the maximum power transmission efficiency intoconsideration. Further, an algorithm, a program or an applicationrequired for the control which is read from a storage unit (not shown)of the wireless power transfer system-device 2000 may be used to controlan overall operation of the wireless power transfer system-device 2000.Meanwhile, the transmission side controller 1510 may signify amicroprocessor, a micro-controller unit or a micom. The transmissionside communication unit 1520 may communicate with a reception sidecommunication unit 2620, and for an example of a communication scheme, aBluetooth scheme may be used. The transmission side communication unit1520 and the reception side communication unit 2620 may transceivecharging status information and charging control command with eachother. In addition, the charging status information may include a numberof the wireless power transfer system-device 2000, a residual energy ofa battery, a number of charging operations, an amount of usage, acapacity of the battery, a ratio of the battery and an amount oftransferred power of the wireless power transfer system-charger 1000.Further, the transmission side communication unit 1520 may transmit acharging function control signal to control a charging function of thewireless power transfer system-device 2000, and the charging functioncontrol signal may indicate to enable or disable for receiving wirelesspower of controlling the wireless power transfer system-device 2000.

Meanwhile, the wireless power transfer system-charger 1000 may include ahardware different from the transmission side communication unit 1520 sothat the wireless power transfer system-charger 1000 may communicate inan out-band type.

In addition, the wireless power transfer system-charger 1000 and thetransmission side communication unit 1520 may be implemented as singlehardware, so that the wireless power transfer system-charger 1000 maycommunicate in an in-band type. Further, the transmission sidecommunication unit 1520 may be separately provided from the transmissionside controller 1510, and the reception side communication unit 2620 maybe included in the controller 2610 of the reception device or separatelyprovided from the controller 2610 of the reception device.

FIG. 4 is a block diagram showing a wireless power transfersystem-device, which is one of a sub-system constituting the wirelesspower transfer system.

Referring to FIG. 4, the wireless power transfer system may include thewireless power transfer system-charger 1000 and the wireless powertransfer system-device 2000 which wirelessly receives power from thewireless power transfer system-charger 1000, in which the wireless powertransfer system-device 2000 may include a reception side coil unit 2100,a reception side impedance matching unit 2200, a reception side AC/DCconverter 2300, a DC/DC converter 2400, a load 2500 and a reception sidecommunication and control unit 2600.

The reception side coil unit 2100 may receive the power through themagnetic induction scheme or the magnetic resonance scheme. Accordingly,the reception side coil unit 2100 may include at least one of aninduction coil and a resonance coil according to the power receptionscheme. In addition, the reception side coil unit 2100 may furtherinclude Near Field Communication. Further, the reception side coil unit2100 may be same as the transmission side coil unit 1400, and aspecification of a reception antenna may vary according to an electricalcharacteristic of the wireless power transfer system-device 2000.

The reception side impedance matching unit 2200 may match the impedancebetween the wireless power transfer system-charger 1000 and the wirelesspower transfer system-device 2000.

The reception side AC/DC converter 2300 generates a DC signal byrectifying the AC signal outputted by the reception side coil unit 2100.

The reception side DC/DC converter 2400 may control a level of the DCsignal outputted by the reception side AC/DC converter 2300 in matchwith the capacitance of the load 2500.

The load 2500 may include a battery, a display, an audio output circuit,a main processor and various sensors.

The reception side communication and control unit 2600 may be activatedby a wake-up power from the transmission side communication and controlunit 1500, communicate with the transmission side communication andcontrol unit 1500, and control a sub-system of the wireless powertransfer system-device 2000.

A plurality of a single wireless power transfer system-device 2000 maybe provided to simultaneously and wirelessly receive energy from thewireless power transfer system-charger 1000. In other words, in thewireless power transfer system using the magnetic resonance scheme, aplurality of the wireless power transfer system-devices 2000 may receivepower from one wireless power transfer system-charger 1000. In thiscase, the transmission side matching unit 1300 of the wireless powertransfer system-charger 1000 may adaptively match the impedance betweenthe wireless power transfer system-devices 2000. This may be similarlyemployed even when the magnetic induction scheme includes a plurality ofcoil units which are independent from each other.

In addition, when a plurality of the wireless power transfersystem-devices 2000 are provided, the systems may have the same powerreception scheme or different power reception schemes. In this case, thewireless power transfer system-charger 1000 may be a system transmittingpower in the magnetic induction scheme or the magnetic resonance schemeor a system using both schemes.

Meanwhile, when a size and a frequency of the signal of the wirelesspower transfer system are examined, in the case of the magneticinduction scheme, the transmission side AC/DC converting unit 1100 mayreceive an AC signal of 110 V to 220 V and 60 Hz, convert the AC signalto a DC signal of 10 V to 20 V and output the DC signal in the wirelesspower transfer system-charger 1000, and the transmission side DC/ACconverter 1200 may receive the DC signal and output an AC signal of 125kHz. In addition, the wireless power transfer system-device 2000receives the AC signal of 125 KHz and converts the AC signal to a DCsignal of 10 V to 20 V, and the reception side DC/DC converter 2400 mayoutput the DC signal, for example a DC signal of 5 V, appropriate forthe load 2500 and transfer the DC signal to the load 2500. In addition,in the case of the wireless power transmission using the magneticresonance scheme, the transmission side AC/DC converter 1100 may receivean AC signal of 110 V to 220 V and 60 Hz, convert the AC signal to a DCsignal of 10 V to 20 V and output the DC signal, and the transmissionside DC/AC converter 1200 may receive the DC signal and output an ACsignal having a frequency of 6.78 MHz in the wireless power transfersystem-charger 1000. Further, the reception side AC/DC converter 2300may receive the AC signal having the frequency of 6.78 MHz, convert theAC signal to a DC signal having a voltage of 10 V to 20 V, and outputthe DC signal, the DC/DC converter 2400 may output a DC signal, forexample the DC signal of 5 V, appropriate for the load 2500 and transferthe DC signal to the load 2500.

FIG. 5 is a block view showing a wireless power transmission apparatusaccording to the embodiment.

Referring to FIG. 5, the wireless power transmission apparatus accordingto the embodiment may include an AC-DC converting unit 3100, atransforming unit 3200, a main control unit 3300, a transmission controlunit 3400, a switch unit 3500, a power converting unit 3600, a matchingunit 3700 and a coil unit 3800.

The AC-DC converting unit 3100 may convert AC power received from apower supply unit 30 into DC voltage.

The transforming unit 3200 may adjust a level of the DC power outputfrom the AC-DC converting unit 3100 based on a control signal.

Since the operation of the transforming unit 3200 is based on theconversion of a DC input into a DC output, the transforming unit 3200may be called an SMPS (Switched Mode Power Supply), a DC-DC transformeror a DC-DC converter.

The transforming unit 3200 may include one of a buck converter of whichan output voltage is lower than an input voltage, a boost converter ofwhich an output voltage is higher than an input voltage, and abuck-boost converter having the characteristics of the above-mentionedconverters.

A control unit may include the main control unit 3300 and thetransmission control unit 3400.

The main control unit 3300 may control the level of DC voltage outputfrom the transforming unit 3200 by taking into consideration the maximumpower transmission efficiency, the amount of power required by thereceiver and an amount of charge in the receiver.

In addition, the main control unit 3300 may control the transmissioncontrol unit 3400 according to the power transmission scheme. The maincontrol unit 3300 may obtain information about the charge scheme fromthe receiver to control the transmission control unit 3400 according tothe power transmission scheme.

The transmission control unit 3400 may include a first transmissioncontrol unit 3410 and a second transmission control unit 3420.

The first and second transmission control units 3410 and 3420 maycontrol the power transmission according to the power transmissionscheme.

The first transmission control unit 3410 may be a control unit tocontrol power transmission through the electromagnetic induction schemein a first charging scheme. That is, the first transmission control unit3410 may control the operation for transmitting power to the wirelesspower reception apparatus through the electromagnetic induction scheme.Preferably, the first transmission control unit 3410 may be a wirelesspower consortium (WPC) controller. The WPC controller may control theoperation for transmitting power to the wireless power receptionapparatus located in a near field through the magnetic induction scheme.In addition, when the wireless power reception apparatus is detectedwithin a critical distance, the WPC controller may control the operationto transmit power to the wireless power reception apparatus. In thiscase, the power transmission frequency may be in the range of 110 KHz to205 KHz. In addition, the second transmission control unit 3420 may be acontrol unit to control power transmission through the resonance schemein a second charging scheme. That is, the second transmission controlunit 3420 may control the operation for transmitting power to thewireless power reception apparatus through the resonance scheme of thepower transmission schemes. Preferably, the second transmission controlunit 3420 may be an alliance for wireless power (A4WP) controller. Whencompared to the WPC controller, the A4WP controller can control theoperation for transmitting power to the wireless power receptionapparatus located far from the A4WP controller. In addition, the A4WPcontroller may include an A4WP Bluetooth (A4WP BLU) controller.Accordingly, when the power is transmitted to the wireless powerreception apparatus through the magnetic resonance scheme, the A4WP BLUcontroller may perform the Bluetooth communication with the wirelesspower reception apparatus. That is, the A4WP BLU controller may receivewireless charging information and status information of the wirelesspower reception apparatus through the Bluetooth communication, andcontrols to transmit an operation control signal to the wireless powerreception apparatus. The A4WP BLU controller may set the frequency forthe power transmission differently from the frequency for the Bluetoothcommunication. Preferably, the frequency for the power transmission maybe 6.78 MHz, and the frequency for the Bluetooth communication may be2.4 GHz. The first and second transmission control units 3410 and 3420may not be limited to the above.

The first transmission control unit 3410 may detect the wireless powerreception apparatus and may be enabled or disabled to transmit the powerthe wireless power reception apparatus under the control of the maincontrol unit 3300.

The first transmission control unit 3410 may be activated prior to thesecond transmission control unit 3420 under the control of the maincontrol unit 3300. In the activation state, the first transmissioncontrol unit 3410 may detect the wireless power reception apparatus andmay check whether the detected wireless power reception apparatus iswirelessly charged through the first charging scheme. Upon checking thecharging scheme of the wireless power reception apparatus, if the firstcharging scheme is adopted in the wireless power reception apparatus,the first transmission control unit 3410 may control the operation totransmit the power to the wireless power reception apparatus. Inaddition, the first transmission control unit 3410 may operate based onthe information about the charging scheme obtained from the receiverunder the control of the main control unit 3300.

If the detected charging scheme is not the first charging scheme, theenabled first transmission control unit 3410 may be disabled under thecontrol of the main control unit 3300.

In a state that the first transmission control unit 3410 is disabled,the second transmission control unit 3420 may be enabled under thecontrol of the main control unit 3300. That is, the second transmissioncontrol unit 3420 is enabled in a state that the first transmissioncontrol unit 3410 is disabled, so that the second transmission controlunit 3420 may detect the charging scheme of the wireless power receptionapparatus under the control of the main control unit 3300. If the secondcharging scheme is adopted in the wireless power reception apparatus,the second transmission control unit 3420 may control the operation totransmit the power to the wireless power reception apparatus. Inaddition, the second transmission control unit 3420 may operate based onthe information about the charging scheme obtained from the receiverunder the control of the main control unit 3300.

Although it has been described in that the first transmission controlunit 3410 is primarily enabled and the second transmission control unit3420 is enabled when the first transmission control unit 3410 isdisabled under the control of the main control unit 3300, the embodimentis not limited thereto. The first and second transmission control units3410 and 3420 may be alternately operated.

The switch unit 3500 may be switched under the control of the maincontrol unit 3300 in such a manner that the power generated from thetransforming unit 3200 according to the charging scheme of the wirelesspower reception apparatus based on the operation of the first and secondtransmission control units 3410 and 3420 can be transferred to one of aresonance coil or an induction coil.

When the induction power transmission scheme is adopted, the switch unit3500 may be switched according to a control signal of the main controlunit 3300 in such a manner that the power generated from thetransforming unit 3200 can be output to a first power converting unit3610. In addition, when the magnetic resonance power transmission schemeis adopted, the switch unit 3500 may be switched according to a controlsignal of the main control unit 3300 in such a manner that the powergenerated from the transforming unit 3200 can be output to a secondpower converting unit 3620.

The switch unit 3500 may include one of an analog switch, a MOSFET and atransistor to perform a switching operation. The switch unit 3500 is notlimited to the above, but various devices can be adopted if they can setthe path through the switching operation.

The power converting unit 3600 may convert a DC voltage of apredetermined level into an AC voltage by a switching pulse signal in aband of several tens of KHz to several tens of MHz to generate power.The power converting unit 3600 may convert a DC voltage into an ACvoltage to generate “wake-up power” or “charging power” used for thereceiver to be charged. The wake-up power may be a micro power of 0.1mWatt to 1 mWatt. The charging power may be a power necessary to chargea battery of the receiver or consumed to operate the receiver. Thecharging power may be in the range of 1 mWatt to 200 Watt consumed inthe load of the receiver.

The power converting unit 3600 may include a power amplifier foramplifying the DC voltage output from the transforming 3200 according toa switching signal of the switch unit 3500.

The power converting unit 3600 may include an inverter. The powerconverting unit 3600 may convert a DC signal output from thetransforming unit 3200 into an AC signal and adjust a frequency of theconverted AC signal according to the power transmission scheme and underthe control of the control unit. To this end, the power converting unit3600 may include a full-bridge inverter or a half-bridge inverter. Inaddition, the transmission side DC/AC converting unit 1200 may includean oscillator for generating a frequency of an output signal and a poweramplifier for amplifying the output signal.

The power converting unit 3600 may include a first power converting unit3610 and a second power converting unit 3620 according to the chargingscheme of the wireless power reception apparatus and may be operatedunder the control of the main control unit 3300 and the transmissioncontrol unit 3400.

The first power converting unit 3610 and the second power convertingunit 3620 may perform the power transmission through mutually differentschemes.

The first power converting unit 3610 may supply power to an inductioncoil 3810 through the magnetic induction scheme under the control of thefirst transmission control unit 3410. In addition, the second powerconverting unit 3620 may supply power to a resonance coil 3820 throughthe resonance scheme under the control of the second transmissioncontrol unit 3420.

The first power converting unit 3610 and the second power convertingunit 3620 may generate AC signals having mutually different frequenciesaccording to transmission schemes, respectively. Preferably, the firstpower converting unit 3610 may generate an AC signal of 110 KHz to 205KHz under the control of the first transmission control unit 3410according to the induction scheme (WPC) which is the first chargingscheme. In addition, the second power converting unit 3620 may generatean AC signal of 6.78 KHz under the control of the second transmissioncontrol unit 3420 according to the resonance scheme (WPC) which is thesecond charging scheme.

The matching unit 3700 may include at least one of at least one passiveelement and at least one active element. The matching unit 3700 performsthe impedance matching between a wireless power transmission apparatus3000 and a receiver, so that power transmission efficiency may bemaximized

The matching unit 3700 may include a first impedance matching unit 3710and a second impedance matching unit 3720 according to the transmissionscheme. The first impedance matching unit 3710 and the second impedancematching unit 3720 may be connected to the first power converting unit3610 and the second power converting unit 3620 of the power convertingunit 3600, respectively.

The first impedance matching unit 3710 may perform the impedancematching with respect to the power output from the first powerconverting unit 3610 when the power transmission scheme is the magneticinduction scheme. The second impedance matching unit 3720 may performthe impedance matching with respect to the power output from the secondpower converting unit 3620 when the power transmission scheme is theresonance scheme.

The coil unit 3800 may include a first coil unit 3810 and a second coilunit 3820 according to the transmission scheme.

When the first charging scheme, that is, the magnetic induction schemeis adopted to the wireless power reception apparatus, the first coilunit 3810 may transfer the power output from the first impedancematching unit 3710 to the wireless power reception apparatus.

In addition, when the second charging scheme, that is, the resonancescheme is adopted to the wireless power reception apparatus, the secondcoil unit 3820 may transfer the power output from the second impedancematching unit 3720 to the wireless power reception apparatus.

In addition, the number of the first and second coil units 3810 and 3820may be singular or plural. When a plurality of first and second coilunits 3810 and 3820 are provided, they may overlap each other and theoverlapping area is determined by taking into consideration a deviationof magnetic flux density and interference of the magnetic field.

The wireless power transmission apparatus 3000 may include acommunication unit. The communication unit may perform bi-directionalcommunication with a communication unit provided in the wireless powerreception apparatus through a predetermined communication scheme, suchas NFC (Near Field Communication), Zigbee communication, infraredcommunication, visible light communication, or Bluetooth communication.

In addition, the communication unit may transceive power informationwith the wireless power reception apparatus. The power information mayinclude at least one of a capacity of the receiver, residual energy of abattery, the number of charging operations, an amount of use, a datarate. In addition, the communication unit may transmit a chargingfunction control signal for controlling a charging function of thereceiver based on the power information received from the receiver.

The charging function control signal may be a control signal forcontrolling the receiver such that a charging function is enabled ordisabled.

The communication unit may perform the out-band communication or in-bandcommunication.

Hereinafter, the wireless power transmission operation of the wirelesspower transmission apparatus having the above configuration according toan embodiment will be described with reference to FIG. 6.

FIG. 6 is a flowchart showing a wireless power transmission operationaccording to one embodiment.

Referring to FIG. 6, the main control unit 3300 may activate the firsttransmission control unit 3410 (S602) and output a signal for detectingthe receiver (S604).

The main control unit 3300 may check whether the receiver is detectedbased on a response signal from the receiver in response to the outputsignal (S606).

If the response signal from the receiver in response to the outputsignal is detected, it may be determined that the receiver has the firstcharging scheme to which the power transmission is performed under thecontrol of the first transmission control unit 3410. Thus, the maincontrol unit 3300 may receive the charging information including anamount of required charge from the receiver (S608).

Thus, the main control unit 3300 may control the first transmissioncontrol unit 3410 based on the charging information to generate powerthrough the first charging scheme and output the power to the receiver(S610).

Meanwhile, if the response signal is not received from the receiver orif the receiver is not detected even if the first transmission controlunit 3410 is activated, the main control unit 3300 may change the statusof the first transmission control unit 3410 into the deactivated state(S612).

Then, the main control unit 3300 may change the status of the secondtransmission control unit 3420 from the deactivated state into theactivated state (S614).

As the second transmission control unit 3420 is activated, the maincontrol unit 3300 may output a signal for detecting the receiver (S616).

The main control unit 3300 may determine whether the receiver isdetected by checking whether the response signal in response to theoutput signal is received from the receiver (S618).

If the response signal from the receiver in response to the outputsignal is detected, it may be determined that the receiver has thesecond charging scheme to which the power transmission is performedunder the control of the second transmission control unit 3420. Thus,the main control unit 3300 may receive the charging informationincluding an amount of required charge from the receiver (S620).

Thus, the main control unit 3300 may control the second transmissioncontrol unit 3420 based on the charging information to generate powerthrough the second charging scheme and output the power to the receiver(S622).

In the above embodiment, it has been described in that the receiver isdetected by activating/deactivating the transmission control units underthe control of the main control unit 3300. However, it is also possibleto request the charging scheme information to the receiver through thecommunication unit to control the transmission control units based onthe charging scheme information received from the receiver by receivingthe response signal.

What is claimed is:
 1. A wireless power transmission method of awireless power transmitter, the method comprising: detecting a firstwireless power receiver for charging through a first power transmissionscheme; attempting to charge the first wireless power receiver when thefirst wireless power receiver is detected; proceeding to charge thefirst wireless power receiver to a first charging power; detecting asecond wireless power receiver for charging through a second powertransmission scheme when the first wireless power receiver is notdetected or when charging the first wireless power receiver fails evenafter the wireless power transmitter attempted to charge the firstwireless power receiver; attempting to charge the second wireless powerreceiver when the second wireless power receiver is detected; andproceeding to charge the second wireless power receiver to a secondcharging power.
 2. The method of claim 1, wherein the second chargingpower is greater than the first charging power.
 3. The method of claim1, wherein the first charging power has a first charging frequency, andthe second charging power has a second charging frequency, and whereinthe second charging frequency is higher than the first chargingfrequency.
 4. The method of claim 1, wherein the first powertransmission scheme includes a negotiation step through an in-bandcommunication scheme.
 5. The method of claim 1, wherein the second powertransmission scheme includes a negotiation step through an out-bandcommunication scheme.
 6. The method of claim 5, wherein the out-bandcommunication scheme is performed by using Near Field Communication(NFC) or Bluetooth communication.
 7. The method of claim 1, furthercomprising: detecting a third wireless power receiver for chargingthrough a third power transmission scheme when the second wireless powerreceiver is not detected or when charging the second wireless powerreceiver fails even after the wireless power transmitter attempted tocharge the second wireless power receiver; attempting to charge thethird wireless power receiver when the third wireless power receiver isdetected; and proceeding to charge the third wireless power receiver toa third charging power.
 8. The method of claim 7, wherein the thirdcharging power is different from the first charging power or the secondcharging power.
 9. The method of claim 7, wherein the third chargingpower has a third charging frequency, and wherein the third chargingfrequency is different from the first charging frequency or the secondcharging frequency.
 10. The method of claim 7, wherein the third powertransmission scheme has an in-band communication scheme or an out-bandcommunication scheme.
 11. A wireless power transmitter comprising: afirst coil for charging based on a first power transmission scheme; asecond coil for charging based on a second power transmission scheme;and a controller configured to: detect a first wireless power receiverfor charging through the first power transmission scheme, attempt tocharge the first wireless power receiver when the first wireless powerreceiver is detected, charge, via the first coil, the first wirelesspower receiver to a first charging power, detect a second wireless powerreceiver for charging through the second power transmission scheme whenthe first wireless power receiver is not detected or when charging thefirst wireless power receiver fails even after an attempt to charge thefirst wireless power receiver, attempt to charge the second wirelesspower receiver when the second wireless power receiver is detected, andcharge, via the second coil, the second wireless power receiver to asecond charging power.
 12. The wireless power transmitter of claim 11,wherein the second charging power is greater than the first chargingpower.
 13. The wireless power transmitter of claim 11, wherein the firstcharging power has a first charging frequency, and the second chargingpower has a second charging frequency, and wherein the second chargingfrequency is higher than the first charging frequency.
 14. The wirelesspower transmitter of claim 11, wherein the first power transmissionscheme includes a negotiation step through an in-band communicationscheme.
 15. The wireless power transmitter of claim 11, wherein thesecond power transmission scheme includes a negotiation step through anout-band communication scheme.
 16. The wireless power transmitter ofclaim 15, wherein the out-band communication scheme includes Near FieldCommunication (NFC) or Bluetooth communication.
 17. The wireless powertransmitter of claim 11, wherein the controller is further configuredto: detect a third wireless power receiver for charging through a thirdpower transmission scheme when the second wireless power receiver is notdetected or when charging the second wireless power receiver fails evenafter an attempt to charge the second wireless power receiver, attemptto charge the third wireless power receiver when the third wirelesspower receiver is detected, and charge the third wireless power receiverto a third charging power.
 18. The wireless power transmitter of claim17, wherein the third charging power is different from the firstcharging power or the second charging power.
 19. The wireless powertransmitter of claim 17, wherein the third charging power has a thirdcharging frequency, and wherein the third charging frequency isdifferent from the first charging frequency or the second chargingfrequency.
 20. The wireless power transmitter of claim 17, wherein thethird power transmission scheme has an in-band communication scheme oran out-band communication scheme.